My English is bad, sorry for that.
Well..
I know, katsklaw going to say "read the conf, there you will find everything"
OK!
This feature is really necesary..
why?
It tracks every registered nick, in the first place.
Second, helps the users to have a documentated data of themselves
Thirth, makes your network looks serious.
And, as an admin you can tell your users in the email that they can just re-read the letter to remember their password or with wich nick they had registered.
In IRC isn't necessary to activate or validate your nick, since you can just delay the registrations.
For example, for people who don't pay attention for the server messages, the email would be great.
Are you not agree?